When you buy a cellphone, it comes locked to the service provider you bought it from. For example, if you buy a Motorola phone from T-Mobile, then the phone is locked to T-Mobile. That means that the phone will ONLY accept simcards from T-Mobile. If you wish to switch providers, you will get an error message as soon as you insert your new simcard into your phone, asking for an unlock code or subsidy password.
In order to keep using the phone with other simcards, you will need to buy an unlock code. The unlock code disables the restriction placed on the phone, allowing you to use any simcard from any other service provider. Once you enter our unlock code, your phone will be unlocked permanently.
Cellunlockcode.com provides unlock codes for 99% of cellphones on the market today, including Blackberry unlock codes, Motorola unlock codes, Samsung unlock codes, LG unlock codes, HTC unlock codes, Palm unlock codes, Pantech unlock codes, Nokia unlock codes, and more.